In order to reduce nitrogen oxide (NO) and nitrogen dioxide (NO2) emissions in exhaust gases, in particular on diesel engines, ammonia (NH3) is generally injected into the gas exhaust system. The ammonia then reacts with the nitrogen oxide (NO) and nitrogen dioxide (NO2) to produce nitrogen and water.
For safety reasons, the ammonia is not stored in its raw form, but in the form of a material generally made by ammonia absorption or adsorption by metallo-chlorous salts. This material thus obtained is then stored in a cartridge.
During use, this cartridge is heated such that the ammonia stored in the cartridge is desorbed, to be injected in gaseous form into the gas exhaust system.
A method is already known from the state of the art, in particular from WO 2006/081824, for manufacturing an ammonia storage cartridge, in particular for a motor vehicle exhaust system, including: a step for providing a material capable of absorbing or adsorbing, and desorbing, ammonia, said material being at least partially saturated with ammonia, a step for producing an intermediate element, including compacting said material so as to form the intermediate element, and a step for stacking at least two intermediate elements in a shell of the cartridge. The effectiveness of the cartridge manufactured using such a method is not optimal, as play may remain between the intermediate elements, and between the intermediate elements and the shell.
This drawback will be resolved by providing a method for manufacturing an ammonia storage cartridge with optimized effectiveness, in particular relative to heat transfers in the cartridge.